Bisphosphonates are known to be useful in the treatment of degenerative bone disorders. Bone degeneration diseases, including Paget's Disease and osteoporosis, have proven difficult to treat because the mechanisms involved are not well understood. Bisphosphonic acid derivatives are known to be osteoselectively taken up by bone tissue. Moreover, bone scanning agents based on the use of some bisphosphonic acid compounds have been used in the past to achieve desirable high definition bone scans (see e.g., U.S. Pat. No. 4,810,486 to Kelly et. al). Other bisphosphonate derivatives have been used as therapeutic agents for bone diseases such as osteoporosis, rheumatoid arthritis, and osteoarthritis (see e.g., U.S. Pat. No. 5,428,181 to Sugioka et. al). Finally, bisphosphonate compounds are known as being useful in inhibiting bone loss, believed to act in a manner which hinders the activity of osteoclasts, so that bone loss is diminished. Bisphosphonate therapy has, however, in the past, frequently been accompanied by severe side effects, such as severe adverse effects on bone development and overall somatic growth.
A need exists for compounds which have the ability to inhibit bone resorption effects and that inhibit mineralization without an increase in toxicity. Moreover, a need exists for compounds that may be useful to deliver bisphosphonates to a cell and within a cell. It is believed that by providing an ability to supply bisphosphonate to a cell, entry ports into the cell can be blocked, thus facilitating various treatment regimens. Alternatively, delivery of bisphosphonate to and within a cell by use of particular delivery agents, may facilitate incorporation into the cell of bisphosphonate compounds which then can be used by the cell in ameliorative ways. A need exists for novel bisphosphonate as a delivery vehicle that can selectively target bone and deliver therapeutic drugs or toxins to bone and surrounding soft tissue, leading to unique and novel treatment regimens. Finally, a need exits or improved bisphosphonate compounds that can aid in bone scanning diagnostics.